This invention relates to the field of control circuits for food preparation machines. More specifically, it relates to a slice control circuit for slicing machines of the type commonly employed for producing prepackaged sliced bacon or cheese. Such machines include a conveyor system on which the product to be sliced is placed. A rotating blade is positioned transversely on the conveyor system in a manner so that the product is sliced as the conveyor moves the product towards the blade. Because the product is moving forward during the slicing there is a pronounced tendency for the slices to be offset from the vertical (FIG. 5) and this creates several problems.
In most cases it is desired that the slices be of uniform thickness and appearance. Under these circumstances waste is created in the form of nonuniform slices at the beginning and end of each slab of product. While this is normally tolerable the problem is compounded where it is necessary to frequently interrupt the slicing process as where a large slab of product is being sliced into small packages. In that case nonuniform slices, usually wedge-shaped in cross-section, are created each time the slicing is interrupted. This waste can amount to a significant loss and it is desirable to avoid such waste where possible.
In an attempt to control this waste it has been proposed to withdraw the unsliced product from the slicer blade each time it is desired to interrupt slicing and to position it, relative to the blade, in a controlled manner when it is desired to resume slicing. By a "controlled manner" it is meant that the product is reinserted into the path of the blade, at a point relative to the angular orientation of the blade, that corresponds to the position that it would have been at if the slicing had not been interrupted. If successfully accomplished, this technique can essentially eliminate waste in the form of nonuniform slices.
A hydraulic system which attempts to reduce waste is disclosed in U.S. Pat. No. 3,140,737 described more fully in the prior art statement which follows. For several reasons that device has not been commercially successful and an improved system is desirable.
It is accordingly an object of the present invention to provide a slice control circuit capable of repetitively positioning a product at a slicing point in correct relationship with a slicing blade so as to eliminate nonuniform slices.
It is a further object of the present invention to provide a conveyor positioning electronic control for a slicing machine which can determine the orientation of the slicing blade and control the conveyor responsive thereto to produce uniform slices.
Another object of the invention is to provide a slice control circuit for a slicing machine which will maintain the conveyor speed in proper relationship with blade velocity during slicing.
A further object of the invention is to provide a control circuit for a slicing machine including switchable means whereby initial positioning of the product can be accomplished at a first rate while subsequent slicing operations are accomplished at a second, slower rate.
Other objects and advantages of the invention will be apparent from the remaining portion of the specification.